Re: [PATCH v2 1/2] xen: introduce header file with section related symbols

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.04.2024 12:02, Roger Pau Monne wrote:
> Start by declaring the beginning and end of the init section.
> 
> No functional change intended.
> 
> Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
>  xen/arch/arm/mmu/setup.c   |  3 +--
>  xen/arch/x86/setup.c       |  3 +--
>  xen/include/xen/sections.h | 17 +++++++++++++++++
>  3 files changed, 19 insertions(+), 4 deletions(-)
>  create mode 100644 xen/include/xen/sections.h

Noticing a few things only after committing / pushing: For one, I should have
waited for an Arm ack. I hope that's not a big issue.

> --- a/xen/arch/arm/mmu/setup.c
> +++ b/xen/arch/arm/mmu/setup.c
> @@ -7,6 +7,7 @@
>  
>  #include <xen/init.h>
>  #include <xen/libfdt/libfdt.h>
> +#include <xen/sections.h>
>  #include <xen/sizes.h>
>  #include <xen/vmap.h>
>  
> @@ -62,8 +63,6 @@ vaddr_t directmap_virt_start __read_mostly;
>  unsigned long directmap_base_pdx __read_mostly;
>  #endif
>  
> -extern char __init_begin[], __init_end[];

Then I wonder why it was this rather than ...

> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -5,6 +5,7 @@
>  #include <xen/param.h>
>  #include <xen/sched.h>
>  #include <xen/domain.h>
> +#include <xen/sections.h>
>  #include <xen/serial.h>
>  #include <xen/softirq.h>
>  #include <xen/acpi.h>
> @@ -309,8 +310,6 @@ void __init discard_initial_images(void)
>      initial_images = NULL;
>  }
>  
> -extern unsigned char __init_begin[], __init_end[];

... this ...

> --- /dev/null
> +++ b/xen/include/xen/sections.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef __XEN_SECTIONS_H__
> +#define __XEN_SECTIONS_H__
> +
> +/* SAF-0-safe */
> +extern char __init_begin[], __init_end[];

... that was moved. "unsigned char" is generally preferred over
declaring binary stuff "strings". I further wonder why the opportunity
wasn't taken to make both array-of-const. And finally I'm slightly
puzzled by the SAF comment appearing with no mention at all in the
description; of course I don't mind its addition.

Jan